1. Field of the Invention
This invention relates to electronic tagging and monitoring systems for subsea use, for example in tagging and monitoring of valves used in subsea pipelines and installations such as trees and manifolds for hydrocarbon production.
2. General Background
The accurate logging of subsea installed devices, such as the positions of valves in subsea trees and manifolds, has in many circumstances been difficult to achieve, particularly with frequent functioning-during installation and commissioning when many different parties may be involved.
The risks associated with not knowing the status of an installed device such as a valve prior to intervention (for example due to incomplete record keeping) are considerable. The valve assembly may sustain damage due to inappropriate torque being applied, or the operator believing that the valve is not functioning correctly if the valve does not move in the expected direction. At the very least, re-establishing the valve status by functioning is a time consuming exercise.
Another problem is positive valve identification, particularly where the marking system has deteriorated, or been damaged, possibly leading to inadvertent operation of the wrong valve.
In general, particularly in deep water, the operation/override of installed devices such as subsea valves is an activity undertaken by ROVs (Remotely Operated Vehicles), and the tools specified are largely similar in design. For valve operation, the torque tool is positioned in the valve interface/receptacle using a manipulator arm or a tool deployment mechanism mounted on the front of the ROV. When the tool is docked, it is located in the receptacle in the valve panel or on the valve. The valve stem has a profile/interface appropriate for the selected tool. When the torque tool is energized, the valve stem is turned and the reaction torque is reacted through the tool to the valve/panel interface, in other words the torque is reacted locally and not through the ROV. The tool basically comprises a hydraulic motor and gearbox with an appropriate drive interface. The problems with the existing arrangements are basically those set out above, resulting from difficulties in arriving at reliable valve (and valve type) identification, and also maintaining an effective log of past valve performance, including previous torque settings.